The present invention relates to a surface mount connector.
Conventionally, a connector such as a card edge connector is used to electrically connect a substrate such as a circuit board to another substrate. (For example, refer to Japanese Patent Application Laid-Open (Kokai) No. H10-335025.) In a connector of such kind, locations of tail portions through which terminals are connected to the substrate are alternately shifted in the transverse direction with respect to the array direction of the terminals in a zigzag form.
FIGS. 7A and 7B are cross sectional views of a conventional connector. Note that FIG. 7A is a cross sectional view showing a first terminal, and FIG. 7B is a cross sectional view showing a second terminal.
As shown in FIGS. 7A and 7B, the connector includes a housing 301 which is formed from an insulating material such as synthetic resin, and first terminals 311A and second terminals 311B which are formed from a conductive material such as metal and mounted on the housing 301. The first terminals 311A and the second terminals 311B are mounted on the housing 301 so that the terminals are alternately located with respect to the array direction of the terminals (the direction perpendicular to the drawings). Also, the housing 301 is attached to a substrate 302 such as a mother board by not-illustrated fixing means such as bolts.
Further, the housing 301 has a first cavity 303 into which, a fixing contact portion 312 and a spring contact portion 313 of each of the first terminals 311A and the second terminals 311B are accommodated. Moreover, a press-fit portion 315 is connected to the fixing contact portion 312 of each of the first terminals 311A and the second terminals 311B via a bent back portion 314, and the press-fit portion 315 is press-fitted into a second cavity 304 of the housing 301, and fixed thereto. Further, a lower end portion 317 is connected to the press-fit portion 315 via a curved portion 316, and the lower end portion 317 is inserted into a through hole 306 of the substrate 302 and soldered. Because of this, the first terminals 311A and the second terminals 311B are electrically connected to not-illustrated conductive traces which are connected to the corresponding through holes 306. Since the lower end portion 317 is soldered from the back side (the right side in the drawings) of the substrate 302, a solder fillet 321 is formed. Also, since melted solder flows through a gap in the through hole 306 due to a capillary phenomena, a solder fillet 322 is formed on the surface of the substrate 302 as well.
As seen from the comparison between FIGS. 7A and 7B, locations of the lower end portions 317 of each of the first terminals 311A and the lower end portion 317 of each of the second terminals 311B are shifted from each other in the transverse direction (the vertical direction in the drawings) with respect to the array direction of the terminals. Note that the through holes 306 are also provided to correspond to the lower end portions 317. Therefore, the locations where the lower end portions 317 are connected to the base bard 302 are in the zigzag form. Further, a cut-out 305 is formed in the end portion of the housing 301 on the substrate 302 side. Hence, it can be checked whether or not the lower end portions 317 and the through holes 306 are soldered appropriately, by viewing the solder fillets 321 from the back side of the substrate 302, and by viewing the solder fillets 322 from the front side of the substrate 302.
Nevertheless, in the conventional connector described above, since the lower end portions 317 are inserted into the through holes 306 of the substrate 302 and soldered thereto, the connector has not been able to be used for high-density mounting. Generally, in the high-density mounting where electronic parts and connectors are mounted on a substrate at high density, electronic parts and connectors are mounted on both sides of a substrate. However, in the conventional connector, since the lower end portions 317 project on the back side of the substrate 302, no other connectors and electronic parts can be mounted on the back side of the connector. Moreover, since a substrate used for high-density mounting generally has a shield plate inserted inside, and if through holes are formed, the shield will not function. However, in the conventional connector, since the lower end portions 317 need to be inserted into the through holes 306, the connector cannot be mounted on a substrate in which a shield plate is inserted. The conventional connector is originally a card edge connector for connecting a substrate to another substrate, and therefore is not envisaged to be used for high-density mounting in which micro-sized electronic parts and connectors are mounted on a substrate at a high density.